PROCESS FOR THE STEREOSELECTIVE PREPARATION OF A HETERO-BICYCLIC ALCOHOL ENANTIOMER

摘要

The invention relates to a method for the stereoselective preparation of a hetero-bicyclic alcohol enantiomer, characterized in that a substantially pure enantiomer of the general formula wherein X is O, S, NH or N-(C1-C4)alkyl; Y1 and Y2 are each independently hydrogen or substituents selected from halogen, (C1-C4)alkyl, (C1-C4)alkoxy, (C1-C4)haloalkyl, formyl, nitro and cyano; the C*-atom has either the R or the S configuration; is prepared from a compound of the general formula wherein R1 is hydrogen or a suitable protective group and R2 is hydrogen or wherein R1 and R2 together form an optionally mono- or di-(C1-C3)alkyl substituted methylene bridge; by the following successive reaction steps: (i) reaction with a compound of the general formula wherein Z is a hydroxy group or a suitable leaving group, R3 is a hydroxy-protective group and R4 is a halogen atom; or wherein R3 and R4 together constitute a valence bond or a biradical of the formula -C(R11)2-O-, wherein R11 is a straight or branched (C1-C4)alkyl group and wherein the C*-atom has either the R or the S configuration; (ii) subjection of the compound formed to a deprotection/ring-closure reaction; (iii) optionally deprotection of the hydroxy group of the ring-closed product. The invention further relates to enantiomerically pure intermediates, the preparation of these intermediates and the preparation of a starting compound.